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Li-ion batteries - Keep on charger?

02-23-2008, 10:58 AM

According to the manual for the Li-Ion batteries/chargers it says that the charger will keep the battery full if left on the charger. I know with Ni-Cad battery, many advised to not store on charger all the time, but what about the Li-Ion? Can I safely keep a battery on the charger for weeks at a time so that I always have a full battery on hand when needed?

Don't know what others may say, but I personally don't. The lithium ion batteries are supposed to be a much better technology, in that they don't have the slow drain that NiCads are susceptable to. That way, you can charge a NiCad and a Lithium Ion on the same day, put them in a drawer, and come back 6 months later, and the nicad will have a 40% charge, and the lithium ion will have a 85% charge (just picked a number for example, don't know if that's anywhere near accurate or not). Therefore, with a lithium ion, there's not as much of a need to keep the battery on the charger for an extended period of time just for "top up" purposes. In my mind, I think that could potentially lead to a problem at some point, in that you have a charger that is constantly on and monitoring the battery - I think a long slow wattage drain on your power bill, a big waste over time for the small percentage that it would keep topped up. Others may have a different opinion (we have lots of engineering types on here, and hopefully one will better help explain my position once they see this thread). But I just think that if you're not using an electrical item, why leave it plugged in and on? You don't leave your bedroom lights on 24/7, so why have that consistent draw with the charger?

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Personally, I wouldn't. Li-ion batteries do have an advantage because they can retain more charger per weight/size than NiCads, and as mentioned previously, may well hold a charge longer. But with regards to longevity, that have been some recent reports of Li-ion batteries discharging much faster in cold environments... so the verdict may still be out there on that issue.

My biggest concern with keeping a Li-ion on charge forever is simply the rather large number of reports of fires that have been reported. One of the hold-ups on getting Li-ions to market was their instability at times. I'm not sure where the problem is exactly, but until I do know, I wouldn't leave it on the charger.

When Ni-Cads first came out, it was recommended that they be left on the charger too, and it wasn't long before that proved to be a bad recommendation. Back then, it took several hours to charge such batteries, so I could understand the recommendation. However today, charging only takes 20 or 30 minutes. I think I'd charge as needed.

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I agree with all the above comments. They are basically true as far as they go and it points to the wide variablility of battery needs.

As a retired electronic technician with a lot of experience with batteries, there are too many variables to the problem of battery maintenance for a simple answer. The best you can do is to follow the manufacturer's recommendation, use only the charger that came with the tool, and hope they don't make much money on their replacement batteries. Go to their distributors and see what they charge for replacements. Then Google the battery and see what others charge.

I don't leave any batteries on extended charge. I store them in fully charged condition and after 3 months discharge and recharge them. That may seem wasteful if the tool is not being used but look at their life expectancy. The shortest I've seen is 500 charge cycles. Divide that by 3 months and you have 125 years. Even a well maintained battery is going to age severely in 10 years, not to mention the guaranteed obsolescence with the march of technology. If you use them daily it is not an issue -- charge it after extended use. The best thing you can do to preserve battery life is to store them fully charged and charge them as soon as the tool slows in order to prevent reverse charging of the weakest cell.

Just my opinion, Jon

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I have a friend in Austin that went to Home Depot and he was asking the sales rep there about nicad batteries verses li-ion batteries. The sales rep told him that the nicad batteries are being phased out in 2009. Do you know anything about that? if it is true, do you have any idea what RIGID will do about the products that people are buying today that required nicad battery use? I wonder if they will develope a li-ion battery that will replace the nicad using the same charger. Is that a possibility?

I have a friend in Austin that went to Home Depot and he was asking the sales rep there about nicad batteries verses li-ion batteries. The sales rep told him that the nicad batteries are being phased out in 2009. Do you know anything about that? if it is true, do you have any idea what RIGID will do about the products that people are buying today that required nicad battery use? I wonder if they will develope a li-ion battery that will replace the nicad using the same charger. Is that a possibility?

First, welcome to the forum. Second (and you will learn this soon as a member of the forum), you will learn to take anything you hear from a HD apron with a grain of salt. Granted, there are some good HD aprons (and we've got a couple of great ones on here). However, some of them blather out some rather absurd things from time to time - if it is so out-of-whack with everything that you know, in all likelihood it is horsecrap. Now, NiCads may be phased out by one particular manufacturer or another in the next year or two, but you'll probably see this tried and true battery technology around for quite a while yet. NiCad has been around for decades, and probably will continue to do so.

And FYI, a tool does not "require nicad battery use". A tool only requires correct voltage, and a battery that fits with the tool. Therefore, one of Ridgid's older original NiCad 18 volt drills from a few years ago can work, and work fine, with Ridgid's new 18 volt lithium ion batteries. A tool does not hinge on a battery's chemistry or Ah, only on it being the correct voltage and connection type.

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that's what i thought, and i did tell my friend that it would be odd to phase this battery out entirely. i also did tell him the same thing about any battery with the same voltage would work as long as the battery would mount up to the tool. i knew there were problems with the li-ion battery overheating, so why would a company get rid of the nicad so soon without a reliable replacement. thanks for dispelling this issue. i will relay the info, thanks....

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well people have different opinions on Lithium batteries because they say it doesn't have the memmory effect that the nicad's have, but just like with cell phones after 2 years the battery doesn't hold the charge as long. Most people as soon as they get home charge their phones. I charge my batteries and set them aside and if and when I need them I charge them real quick. I never leave them on the charger if not in use. In the Air Force we don't leave our tools charging. We charge them and then store them, then every month we have an inspection and we test the voltages to make sure they are in tolerance.

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I'm sorry guys -- I forgot to say in my reply on 2/24 that my experience is with NiCad and NiMH batteries. It's about time I learned about Li-Ion batteries so I went searching and found a comprehensive article on Wikipedia. It exploded a few of my beliefs, especially about storage and life expectancy. The summary is near the end but the "why" is scattered throughout the article.

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We use a large number of ridgid cordless power tools in our company. I have noticed the 24V LI batteries self discharging fairly quickly sitting on the shelf. I would say it is quite common for a 25% discharge in a couple of weeks. A number of others have noticed this tendency and commented on it in this forum. Some feel it is due to the self diagnosing circuit in the batt.
It is relativly easy to monitor the charge status of the 24V LI with its built in fuel guage. The 18V LI is another matter, however I have put one of them on a charger after letting it sit for a couple of weeks and noted a fairly lengthy charge time therefor am assuming some significant amount of self discharge with this battery also.
We use our tools every day and recharge on a regular basis, however if I were a home owner with occasional use I would pull my batteries from the charger and charge on a regular basis of every couple of weeks if not used. Maybe the 1st and 15th of the month.
According to the instructions in the Ridgid Lithium Ion tool owners manual Ridgid suggests that for maximum service "batteries should be removed from the charger when fully charged". see here:http://www.ridgid.com/ASSETS/250D08F...094_eng_05.pdf
pg 15.....To obtain the longest possible battery life, we suggest the
following:
For lithium-ion batteries:
 Remove the battery pack from the charger once it is fully
charged and ready for use.

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These batteries are supposed to be able to sit on the shelf for a year and be OK to use without recharge. If they really do lose charge that quickly, the occasional use homeowner is at risk of them running down too low and then not being able to charge them up again.

My tool use is very sporadic. I may use them a lot for a few weeks at a time when doing a project, and then leave them for a few months with hardly any use.

Leaving NiCds for a few months is no problem, they charge up OK whenever I need them. I don't think I am disciplined enough to ensure I would charge batteries every 2 weeks.

Even with LSA, this would not be acceptable.

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So - I am reading that the Ridgid Li-Ion batteries will fit in the Nicad tools like the R844 sawzall and hammerdrill?? I cannot tell compatibility just by looking at them. I like the 'lasting' power of Li-ion so just might invest in batt & charger

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I was in my local HD here in San Antonio and decided to price a new battery charger for a back-up and as I rounded the corner where the chargers and batteries are I noticed a nice yellow Home Depot sticker that read $39.00 was $79.00 . This sticker was for the 18v Max 2.5 Ah Ridgid batteries and so I asked the HD associate if this was gonna be the new price on them and he said "no , that that certain battery was being discontinued " . Im not a big fan of the heavy batteries but I figured what the heck why not for that price , so I bought the last 3 they had.
I called Batteries Plus the other morning to get a price on rebuilding these same batteries and they said $53.99 .

So - I am reading that the Ridgid Li-Ion batteries will fit in the Nicad tools like the R844 sawzall and hammerdrill?? I cannot tell compatibility just by looking at them. I like the 'lasting' power of Li-ion so just might invest in batt & charger

Yes. It doesn't matter the chemistry, just so long as the tool line-up and battery attaches the same (ie - Ridgid, 18 volt).